Forum Discussion
Ray_Ebersole_13
Nimbostratus
NimbostratusDead Server Redirect
Hi,
We have a server that is down with an external DNS and IP address that I would like to point at an internal IP that is correctly working. Here is what I have done:
- Created a node for the working server
- Added that node to a newly created pool
- Created a VS with the external IP that is dead as the VS IP
- Have an iRule that routes traffic from that VS to the Pool
I believe that should work, but it times out and does not redirect. I have also tried pinging the address and it times out too. The only thing that I do see is the DNS name is different from the ping server name that responds.
Anything that you might think That I should be doing any help would be appreciated.
Thanks....Ray
- Kevin_Stewart
Employee
A few questions:
-
Why use an iRule instead of just applying the pool to the VIP?
-
Can you elaborate on "the DNS name is different from the ping server name that responds"?
-
Are you pinging by name or IP?
-
- Kevin_Stewart
Okay, so DNS issues aside, can you ping the VIP by IP? And can you access the VIP and backend server if using the IP address?
- Kevin_Stewart
Allow me to try to clarify. The original server, the one that is now down, had an IP address that was accessible externally. You took that IP address and reused it to create a VIP, which should also be accessible externally, and so far you can't access it, though you could access the server with that address when it was up. Is that correct? If yes, are you crossing a routed network to get to it? You might be having an ARP issue - a "stuck" layer 2 MAC address mapping from the router connected to that subnet. Usually that'll time out after a while. Is the server truly down, as in powered off?
- Kevin_Stewart
Technically speaking, not being able to RDP to the server doesn't necessarily mean it's powered down. If by chance that server is still powered on but services are offline, the network stack could still be alive and communicating. In any case, assuming the F5 VIP is on the same network as this server, and you can perhaps reach other VIPs on the F5, then it seems purely like a networking issue. The most common thing that happens when you reuse an IP address address is that ARP doesn't reset immediately. A router or switch on that network may still have the hardware address of the old device. Your best bet may be to coordinate with whoever manages the network devices on that network to 1) remove the ARP cache, and 2) sniff the traffic destined for this IP address (to see where it's going).
- Kevin_Stewart
In the meantime you could run a tcpdump capture on the external interface of the F5 just to confirm that you don't see the requests coming to the VIP.
